Gases produced in or infused into the intestinal tract will be used to study intestinal physiology. Information will be obtained on the transit of materials through the gut, blood flow to the intestine, and the action of the intestinal bacteria. BIBLIOGRAPHIC REFERENCES: Levitt, M.D. and Engel, R.R. Intestinal gas. Advances in Internal Medicine, ed. E. Stollerman, Vol. 20:151, 1975. Levitt, M.D. and Duane, W.C. Amylase removal mechanisms. Surgery of the Liver and Pancreas. Ed. Najarian, J.S. and Delaney, J.P. Intercontinental Medical Book Corp., New York, p. 223, 1975.